Rescue from OpenSSL::SSL::SSLError (resolves #4)

Adds a new `IndieWeb::Endpoints::SSLError` class that wraps the
underlying Ruby standard library SSLError raised by the HTTP gem.

_Finally._

Author: jgarber623

README.md

@@ -80,6 +80,10 @@ From [httprb/http](https://github.com/httprb/http):
 
 - `IndieWeb::Endpoints::HttpError`
 
+From the Ruby Standard Library's [`OpenSSL::SSL::SSLError`](https://ruby-doc.org/stdlib-2.6.9/libdoc/openssl/rdoc/OpenSSL/SSL/SSLError.html):
+
+- `IndieWeb::Endpoints::SSLError`
+
 ## Contributing
 
 Interested in helping improve indieweb-endpoints-ruby? Awesome! Your help is greatly appreciated. See [CONTRIBUTING.md](https://github.com/indieweb/indieweb-endpoints-ruby/blob/main/CONTRIBUTING.md) for details.

lib/indieweb/endpoints.rb

@@ -16,6 +16,7 @@ module Endpoints
     class Error < StandardError; end
     class HttpError < Error; end
     class InvalidURIError < Error; end
+    class SSLError < Error; end
 
     # Discover a URL's IndieAuth, Micropub, Microsub, and Webmention endpoints
     #

lib/indieweb/endpoints/client.rb

@@ -43,6 +43,8 @@ def response
                           .get(uri)
       rescue HTTP::Error => e
         raise HttpError, e
+      rescue OpenSSL::SSL::SSLError => e
+        raise SSLError, e
       end
 
       private

spec/lib/indieweb/endpoints/client_response_spec.rb

@@ -12,4 +12,12 @@
       expect { response }.to raise_error(IndieWeb::Endpoints::HttpError)
     end
   end
+
+  context 'when rescuing from an OpenSSL::SSL::SSLError' do
+    it 'raises an IndieWeb::Endpoints::SSLError' do
+      stub_request(:get, url).to_raise(OpenSSL::SSL::SSLError)
+
+      expect { response }.to raise_error(IndieWeb::Endpoints::SSLError)
+    end
+  end
 end